This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A201642 #21 Feb 16 2025 08:33:16 %S A201642 1,12,1211,121121,121121221,12112122122112,1211212212211211221211, %T A201642 121121221221121122121121221121121, %U A201642 1211212212211211221211212211211212212211212212112,12112122122112112212112122112112122122112122121121122122112122122112112122 %N A201642 Successive generations of the variant of the Kolakoski sequence. %C A201642 Word lengths give A042942. %H A201642 Eric Weisstein's World of Mathematics, <a href="https://mathworld.wolfram.com/KolakoskiSequence.html">Kolakoski Sequence</a> %F A201642 Generate A006928 via 1 -> 12 -> 1211 -> 121121 -> 121121221 -> .... %Y A201642 Cf. A006928, A000002. %K A201642 easy,nonn %O A201642 0,2 %A A201642 _Arkadiusz Wesolowski_, Oct 09 2012